The invention relates to novel photopolymerizable compounds, to a photopolymerizable mixture containing said compounds, and also to a photopolymerizable copying material comprising a coating base and a photopolymerizable coating which is composed of the mixture.
DE-C-2,027,467 discloses photopolymerizable mixtures which contain polymeric binders, polymerizable compounds and derivatives of acridine and phenazine as photoinitiators. Some of the representatives of this class of compound, for example 9-phenylacridine, are notable for high photosensitivity. The preferred representatives have the disadvantage that they tend to migrate out of the photopolymerizable coatings and, in particular, out of photocured photoresist coatings in certain kinds of treatment baths, for example acidic electroplating baths, and produce a troublesome yellow coloration therein.
EP-A-11,786 and 220,589 disclose corresponding mixtures which contain certain quinoline derivatives as photoinitiators. These mixtures, too, which are photosensitive like the above-mentioned mixtures, suffer from the same disadvantages.
In the photocured state, the known photopolymerizable materials often have an inadequate mechanical strength and hardness for some purposes. This is particularly true in the applications as solder masks, as permanent resist and as lithographic printing plates.